Tennis alleys or lanes are operated for player practice and the improvement of their game, with the objective of realistic ball delivery and efficient recovery of balls returned by the player. Prior art machines and installations for this purpose have been complex and cumbersome, they have required the storage of a large supply of balls, the acceleration means have been detrimental to ball life, and the automatic simulation of serve variations has not been altogether realistic. Therefore, it is a general object of this invention to realistically serve a small supply of tennis balls, delivering all worn balls substantially the same as new live balls, delivering said balls through a true ground stroke trajectory, and recycling all balls returned to the net.
The cost of operating full tennis courts is more than double that of half-courts; due to the added labor in retrieving balls and investment inventory in a large number of balls. Therefore, it is the half-court with which this invention is particularly concerned, or practice alleys where the player has an opportunity to develop good strokes, good footwork, and good habits by which he can correct and improve his game; or to warm-up before actual play, or simply to develop natural playing ability. To these ends it is an object of this invention to provide a tennis ball server and pick-up system that recycles a small supply of tennis balls, all without alteration to the tennis court or alley floor. With the present invention, there are no pits to dig and/or no downslope required, and elevated structures are avoided; a characteristic feature of the present invention being to serve the ball from beneath the net with moderate overspin and at a speed establishing a trajectory that permits the player to track the ball during the half-court journey; recognizing that the player reaction time is half that for a full court. In this manner the ball stays within the base line of the court to rebound in the manner of a natural serve.
The server operates to deliver tennis balls at both moderate and high velocities, involving an emitter having an inertia wheel to engage and accelerate the balls. Heretofore, elaborate motor controls have been resorted to for driving the inertia wheel at varying rates of speed, but with high costs and maintenance problems. It is an object therefore, to improve the cost and maintenance situation by converting to direct drive from separate prime movers through high and low speed gearing or belting. With the present invention, two identical electrical motors are employed, one with a larger drive pully than the other so as to drive the single inertia wheel at two speeds through one belt, as will be described.
Balls that are returned by the player and which properly pass over the net are stopped in the normal manner by a damping net in the form of a back drop that depends below the top of the playing net and over the transverse ball runs. In this way, all tennis balls that pass over the net or up and over the berm ramp become retrieved balls, and in practice the percentage of these balls is high with respect to the ability of the player. It is an object, therefore, to provide a reliable feeder for charging the server with tennis balls in timed sequence, for example one ball serve every three or four seconds. Heretofore, difficulty has been experienced with ball jambs in the ball runs from back drops, as a result of stoppage at the feeder to the server. In practice, all tennis balls are not of the same diameter and texture, and accordingly the present invention provides an improvement in this respect. With the present invention, a rimmed plate receives tennis balls in bulk in a trough, said plate operating on an inclined plane to form one side of said trough, and having at least one opening therein to form a pocket that selectively engages a single ball and carries it upon an underlying wall having a feed opening that drops said balls one at a time into the emitter of the server. As will be described, the rimmed plate feeder has a self-clearing action to prevent jambs.
The sequence of serve and the placement of rebound at the base line is unique with the present invention. Heretofore, programming for such purposes has been stereotyped and/or inflexible with respect to timing, trajectory, and direction. With the present invention these factors of time, trajectory, and direction are dissimilar so as to produce an unpredictable sequence of serve, not following a determinable pattern but rather a random sequence of indeterminable character. As will be described, the three factors are motor controlled and each functioning on a time base disassociated with the frequencies of the others. Consequently, there is no detectable serve pattern, since the phase proximity of the three dissimilar frequencies is unpredictable as a practical matter.